Lead product and process of producing the same



Patented De; 6, 1927..

UNITED .STATES Io Drawing.

-This invention relates to certain lead products, particularly red-lead, as well as to a method or process of producing the same and it is peculiarly adapted to the recovery of lead values such, for example, as are contained in scrap storage battery plates and the present applicationis in th nature of a continuation of and a substitution for my copending application- Serial No. 610,376 filed January 2nd, 1923,as to com mon su ject matter. disclosed and claimed.

' The primary objects of the invention are the recovery of certain lead values from ma; terial containing lead sulphate such as the scrap battery (plates mentioned and particularly the pro action of a red lead of extremely high quality having properties which impart greatl improved characteristics t0 paints in w iich it is incorporated as a pigment. As a further ob]ect I "recover; the lead oxides and the pure grid metal from such plates in condition to be used again commercially without performing any smelting or reduction process.

More specifica ly considered and with a view to a special use the followingmay be enumerated as objects of the invention: 1)

' .run-or sag when mixed with the desired quantity of raw linseed oil and applied to a'sharply sloping surface; (2) the production of a igment which will make the paint more easi y s read with, the brush; (3) the.

production 0 a pigment which will enable 7 same or similar characteristic'smight; be

the paint to cover at least thirty percent more perfectly than similar fpigments so far a red lead pig-1 ment which can be used in paints in volume in use; (4) the production 0 considerably greater than heretoforef possible; (5) the productionof a 'red lead pigment which when. used .with linseed oilsettles very slowly in. containers;v (6) the production of a pigment which after settling .can be easily stirred up again; and 7) the roduction of a pigment which Wlll. not arden in containers...

In carrying out my invention I prefer to use scrap storage batte plates as my raw material but it will, 0 course, be understood that. any other material having the The "grids offbattery plates are made generally of lead and antimony alloy containing approximately 94% lead and 6% antimony r 1,551,886. PATENT OFFICE;

JAMES o. HANDY, or mrrsnuaen, rnmwsynvnmn; AssIeNon, 'ro rnmos COMPANY, A coltroaa'rron orDELAwABE.

and usually very in impurities or foreign matter. In t e manufacture of the.

ordinary form of lead storage battery plates .the lead antimony alloy is enerally-cast into ids and these are fille with pulverized ead compounds, that employed for 'n'egative plates being generally litharge', PhD, and that for the positive plates generally being a mixture of litharge'andred lead :knogn respect1vely by the symbols PhD and a 4' Y In the action of charging these lead storage batteries, the plates are immersed in sulphuric acid. The electric current operates to change the PbO of the negative plate into metallic lead in spongy or finely divided form while the filler-or active material on peroxide having the symbol PbO The discharge of the battery in service produces lead sulphate known by the s mbol the positive plate is transformed into lead v PbSO in bothplates. Recharging ecomposes most of the lead sulphate.

.In commercial practice the usual guarantee given with aleadaccumulator or storage this is exceeded" the life is thought to be above the average. After thebatteries .80 battery is eighteen months service and if broken up by the recharging process it is the customary "practice to sell the old plates.

scrap dealers and .sold'to the s'melters.

' Generally speaking scrap plate has a composition 'aboutas follows: 50% lead anti- This scrap is ordinarily collected by the mony alloy, 22.5% lead sulphate, 10% lead peroxide, 15f7 -lead monoxide, 2.5% spongy lead. a p Red lead produced by my improved process is particularly adapted for use area pigment in paints and before proceeding with a I description of the invention it should be pointed out-that as at present manufactured the best grades of commercial red'lead conlead and when mixed. with the linseedoil commonly used in paints the two react upon each other in such a. way asto roduce a vyijrm nber of objectionable characteristics such f as early hardening of the paint, etc., as is well known in the art. Inthe manufacture of my improved red lead I greatly reduce the percentage of lith-arge in the finished tain a certain percentage of lith'arge P5 0); 5 0 i Litharge is an active oxygen .compoun product replacing it referably with lead carbonate (PbCO other words I produce a red lead which has as its non-red lead constituent a predominant quantity of lead carbonate instead of litharge. I

Where storage battery'plates are used (as preferred) the first ste in my process is to mechanicall separate the metallic grid from the filler. his I prefer to do by the use of a ball or pebble'mill, corrugated jaw crusher, corrugated rolls, or other suitable device which detaches the more brittle nonmetallicfiller from the, grids, the crushing process by which this. is accomplished being carried far enough to clean even the finer parts of the grids so that they maybe screened out from the filler. This I have foundh to.jnvolve crushing the filler to mesh or in "some cases even to mesh. If any of the rid particles pass they will contaminate fw th lead antimony alloy the urer mixturewvhic h constitutes the filler. ence the necessity for thorough separation by siftingtor floating.

'isevident that where a rolling operation is'used, especially if corrugated rollers areemployed, the disintegrative force is one which will subject the material to a combination of distorting effects involving compressive, torsional and tensional strains, all of which are non-percussive in character.

As a' secon'd step 111 my improved process- Igrind the finely divided filler, in a pebble or tube mill with a suflicient quantity of an alkali metal carbonate solution such, for example, as one of sodium carbonate or of sodium bicarbonate to :decompose the lead sulphate with the production of lead carbonate and sodium sulphate as a by-product in solution, the mill being run until a suitable test shows that the alkali metal carbonate solution has completed its work. Then thesodium sulphate solution is drawn off as com letely as possible and the powdered resi ue is washed with water sufficientlyto remove the remaining. sodium sulphate. The sodium sulphate in the solucessive batches.

lead up to 10%.

The residue is then dried and the cake broken and exposed in layers of suitable depth to the action of natural draft through a furnace preferably of the muflle type at a temperature between 350 and 500 degrees 0., or etter' between 450 and 500 degrees C, At this temperature in a space of from 2 to 6 hours, by the decomposition of the lead carbonate and the interaction of the lead oxides and the spongy lead and by the subsequent combination with the oxygen of the air, a commercial red lead of unusually good quality maybe produced especially as regards fineness of texture and percentageof about 550 C. and if the heating takesplace at 600 to 650 C. 1i ht and fine grained litharge is obtained iaving the usual light brownish color which is desired by the trade.

I find, however, in producing litharge,

that the greatest care must be exercised in 1 separating'the last traces of the more'brit- 'tle lead antimony battery plate substance from the filler for if there be any antimony present in the material during treatment in 1 the furnace it is difficult if not impossible to make a satisfactory litharge in this way. Litha rge, in order tobe acceptable to certain large consumers, must be soluble in dilute nitric acid without leaving more than insignificanttraces of insoluble matter. In order to meet this requirement unfailingly, therefore, I prefer to use negative battery plates only 111 manufacturing litharge according to my invention because, in service, they do not become so brittle as do the positive ones nor do they oxidize as much. Consequently it is easier to obtain complete separation of the-grid substance from the filler innegative plates than it is in positive plates. Otherwise the procedure is similar to that used for the production of red lead exce t for the higher temperature used in the nal treatment in thefurnace.

Furthermore, the intermediate product resulting from the treatment of mixed filler with the alkali metal carbonate solution, by virtue of its high lead carbonate content, constitutes an excellent brown pigment of attractive color without the necessity for further treatment except washing and dry-.

ing. Also the intermediate product result 4 ing from the treatment with alkali metal carbonate solution of negative filler alone makes a very high quality gray pigment. The

roduct contains approximately 50 to 70% ead carbonate, 15 to 25% lead monoxide and up to 15% metallic lead.

I have found it advantageous to use about 10% excess of sodium carbonate and to use it in a strength which preferably does not exceed 10%, that is to say, one part dis solved in nine partsof water, but I have also been able to use-solutions from to saturation successfully although the solution is rather more rapid'in its action.

4, In connection with the use of the strong solution like the saturated one referred to,

it is desirable toadd a small amount of bi-- carbonate of soda as otherwise some of the lea-d may be dissolved and the process there by complicated. An alkali metal bicarbonate may be used b itself or a mixture of the same with an a kali metal carbonate.

In my process it is important to use the alkali metal carbonate solution without the application of heat which greatly reduces the expense besides making it possible to carr out the process of grinding and conversion of the lead sulphate into lead carbonate simultaneously in a pebble mill.

My process regenerates in pure form all of the material used in the manufacture ofstorage'battery plates and also recovers the lead values in the sediment or mud which deposits in storage batteries durmg service since this sediment is simply dislodged filler.

Furthermore the materials may be-readily by the process the material again becomes immediately available for use. The solution 7 may be used at any temperature but there I to use caustic alkali solution in admixture are economic and technical reasons for using it without heating.

My improved process is also applicable to any natural or artificial substancesconsisting of or containing lead sulphate or carbonate as well as to those obtained from storage batteries.

There may be some commercial situations in which it would be allowable or desirable with an alkali metal bicarbonate or normal alkali metal carbonate'or with both but the process as more specifically above describedv is the one that I prefer.

Caustic soda solutions, (sodium hydroxide), converts lead sulphate into hydroxide and sodium sulphate but it hasthe disadvantage of dissolving large quantities of lead which must afterwards he recovered.

. It is to be observed furthermore that the reaction of sodium hydroxide solution on lead sulphate is a reversible one and therefore it is difiicult if not impossible to make I I a complete transformation commercially in this manner and failures have resulted from such attempts. The use of sodium hydroxide is much more expensive and harder on the workmen than is sodium carbonate which I prefer to the other alkali metal carbonates and bicarbonates. 1

V I have found that a red lead pigment produced in the above mannenand havin the above indicatedapproximate analysis w ll be.

in a state of subdivision which is extremely vfine and this contributes greatly to the nonsettling and non-hardeningqualities of a- .paint embodying my product as well. as to its great spreading and covering properties.

Furthermore, the 'fact that the non-red lead constituent of my product contains a. predominant quantity of lead carbonateinstead.

of litharge makes it unusually valuable as a pigment since, when mixed with linseed oil, T

there is minimum disturbance due to reac-' tion between the oil and the litharge, the litharge being substantially reduced in quan tity over what is ordinarily found in the average commercial red l ead. Lead carbonate does not react with linseed oil to groduce I the detrimental effects produced y the union of linseed oil with litharge. A paint, therefore, made with my pigment will not .run or sag when mixed with half its weight of raw linseed oil and painted on a sharply sloping surface. The paint is spread with unusual ease with the brush and can be made to cover the same surface at least 30%'more perfectly than can be done with commercial red lead paint made on the same formula. It is possible to make a paint from my red lead which contains at least twice the volume of red lead which would be contained in paint made from the ordinary commercial red lead product.

Iclaimz' 1. The hereindescribedv process of separating. lead 'values from storage battery waste which comprises mechanically dislodging and separating the brittle parts from i the non-brittle, and then treating the 'dislodged material with a solution of an alkali lolmetal' carbonate without the application-of 'eat.' 7 ,4

2 The herein described process of separat ng lead values from storage batter waste which comprises mechanically dis odging and separating the brittle parts from the non-brittle, treating the dislodged material witha solution of an alkali metal carbonate without the application of heat, separating the residue from the resulting mixture-and then roasting the residue. 3. The herein described process of separating lead values from storage batte waste i which consists inmechanically dis odging and separating the brittle parts from the non-brittle, in treating the dislodged lilaterial with a solution of an alkali metal carbonate without the application of heat, in

withdrawing the resulting solution, in washing the residue, and in roasting the washed product.

4. The herein described process of separating lead values from storage battery plates: which consists in mechanically separating the filler from the grid, in treating the filler so separated with a solution of an alkali meta-l carbonate without. the; application of heat, in ,removing the solution from the residue, and in roasting the residue.

5. In the herein described process of recovering lead values from material contarm ing'metallic lead or lead alloy, lead oxides and leadsulphate, the step which. comprises grinding the material in the presence of an alkali metal carbonate solution.

6. In the herein described process of re- "covering lead values from materialv containing metallic lead or lead alloys, lead oxides and lead, sulphate, the steps which comprise grinding the material in the presence of an alakali metal carbonate solution, drawing ofl:'

- "the resulting alkali sulphate solution, and

washing the residue.

'7. In the herein described process of recovering lead values from material containing metallic lead-or lead alloy, lead oxides and lead sulphate, the steps which comprise grinding the material in the presence of an' alkali metal carbonate solution, separating the liquid from the solid residue, and then roastingthe solid residue.

8. The herein described process of recovering lead values from material containin metallic lead or lead alloy, lead oxides an lead sulphate, which comprises grinding the material in the presence of an alkali metalconstituent a greater proportion of leadcarbonate than of litharge. 11. As anew article of manufacture the product ofv claim 2 characterized as a com mercial oxide of lead of extreme fineness and adaptability to mixture as a pigment with linseed oil. 7

In testimony whereof I. have signed my name.

JAMES o.

hereunto 

